Drain return for engine

ABSTRACT

Disclosed herein is a two-stroke internal combustion engine with a drain return system comprising a drain return line which is supported by wall means defining a fuel supply passage and which extends from a crankcase and includes an end part terminating in adjacently spaced opposing relation to one portion of the wall means, whereby drains exiting from the drain return line splash against the wall portion and are broken into droplets for delivery to the engine cylinder.

U United States Patent 1 1 1 3,730,149 Brown May 1, 1973 1 DRAIN RETURNFOR ENGINE 3,l32,635 5/1964 Heidner ..123/73 A 75 1 z Pt W.B z' ,111. li or e er Primary Examiner-Wendell E. Burns Asslgneer Outboard MarineCorporation, Attorney-Robert E. Clemency, John w. Michael, a g Gerrit D.Foster, Bayard H. Michael, Paul R. Puerner, Jose h A. Gemi nani Andrew0. Riteris Robert K. 22 Fl (1. n. 21, 1971 P g 1 r l 1 I 6 Ja Gerlingand Spencer B. Michael [21] Appl. No; 108,265

[57] ABSTRACT 123/73 A, Disclosed herein is a two-stroke internalcombustion 123/73 B, 123/73 PP, 123/119 B engine with a drain returnsystem comprising a drain [51] Int. Cl ..F02b 33/04 return line which issupported by Wall means d fi i [58] Field of Search ..l23/73 R, 73 A, 73B, a fuel Supply passage and which extends from a Crank 123/73 73 119136 case and includes an end part terminating in adjacently spacedopposing relation to one portion of the [56] References 'i wall means,whereby drains exiting from the drain UNITED STATES PATENTS return linesplash against the :wall portion and are broken into droplets fordelivery to the engine 1,265,89l 5/1918 Ellis ..123/73 B Cylinder.1,308,237 7/l9l9 Goff et al. ..l23/73 B 3,128,748 4/1964 Goggi ..l23/73R 7 Claims, 1 Drawing Figure DRAIN RETURN FOR ENGINE BACKGROUND OF THEINVENTION Two stroke engines commonly experience an accumulation of fueland lubrication drains" in the low point or sump of the enginecrankcase. The desirability of recycling or returning such drains to theengine cylinder for ultimate combustion has been known for some time.Such recycling is especially important in avoiding pollution associatedwith outboard motors as, in the past, such drains have commonly beenwasted overboard into the body of water in which the outboard motor wasoperating.

Prior arrangements for returning or recycling drains are disclosed inthe U.S. Pat. No. 2,717,584 to Upton issued Sept. 13, 1955, the U.S.Pat. No. 3,128,748 to Goggi issued Apr. 14, 1964, and in the U.S. Pat.No. 3,132,635 to Heidner issued May 12, 1964.

The above identified disclosures all rely in some part on the incomingcharge to carry the drains into the cylinder for combustion. However,when the drains are supplied to the charge in the form of a stream, lessthan maximum conditions are presented for effective transportation ofthe drains bythe incoming charge into the cylinder for combustion.

SUMMARY OF THE INVENTION The invention provides an arrangement forbreaking up a stream of drains into droplets so as to facilitatetransportation of the drains into an engine cylinder for ultimatecombustion, either by way of direct transportation of the droplets bythe incoming charge or by increasing the amount of vaporization of thedrains, thereby to facilitate delivery of such vaporized drains to theengine cylinder.

In accordance with the invention, there is provided a drain return linewhich, in part, is supported by a fuel feeding passage, such as thetransfer passage of a twostroke engine, and which includes an end partterminating in closely spaced relation from an opposing portion of thewall defining the fuel feeding passage.

Also in accordance with the invention, the drain return linecommunicates with the crankcase of a twostroke engine and has, forsubstantially the entire length of the return line, a relatively smalldiameter. As

a consequence, the drains exiting from the end part of the drain returnline are particularly responsive to the pressure pulses supplied to thereturn line by the crankcase and, as a result, drains exit from the endpart of the drain return line in a stream having sufficient velocity tocause splashing when the stream strikes the closely spaced opposed wallportion. Such splashing is effective to break the stream up intodroplets which are more readily vaporized and which can be more readilytransported into the cylinder by an incoming fuel charge.

One of the principal objects of the invention is the provision of anarrangement for more effectively transporting return drains into anengine cylinder by an in coming fuel-air charge.

Another principal object of the invention is the provision of anarrangement for causing a returning stream of drains to splash into acharge of fuel-air traveling toward an engine cylinder, whereby to breakthe stream of drains into droplets which can be more effectively borneto the engine cylinder by the incoming charge.

Still another principal object of the invention is the provision of adrain return system including a drain return line which communicateswith the engine crankcase, which has a relatively small internal bore,and which terminates in closely adjacent relation to a wall portiondefining a fuel feeding passage, whereby the pressure applied to thedrains by the crankcase will cause the drains to exit from the returnline in a stream which splashes against the wall portion.

Another important object of the invention is the provision of a drainreturn system which is economical to construct and to install and whichwill provide a long and useful life.

Other objects and advantages of the invention will become known byreference to the following description and accompanying drawings.

DRAWING FIG. 1 is a partially schematic fragmentary sectional view of anengine embodying various of the features of the invention.

GENERAL DESCRIPTION Shown in the drawings is a two-stroke engine 11including an engine block 13 defining a cylinder 17 having an exhaustport 19 and an inlet port 21. Reciprocably movable in the cylinder 17 isa piston 23 which is joined to a connecting rod 27. The intake port 21comprises the terminus of a transfer passage 29 which is defined bysuitable wall means 30 and which constitutes a fuel supply or feedingpassage.

In the particularly disclosed construction, the transfer passage 29communicates with a crankcase 31 which, in turn, is connected throughreed valves (not shown) with a carburetor (not shown) so as toperiodically pump a fuel-air mixture through the transfer passage 29 tothe cylinder 17. As above described, the construction is conventional.

As shown, for instance, in the Heidner U.S. Pat. No. 3,132,635 issuedMay 12, 1964, which is hereby incorporated by reference, drains whichaccumulate in the crankcase can be pumped, by reason of the cyclicalpressure pulses occurring in the crankcase, for return to the enginecylinder and ultimate combustion. Thus, as shown in FIG. 1, there isprovided for the purpose of feeding drains into the cylinder 17 forultimate combustion, a drain return line or duct 41 which communicates"with the crankcase 3i. Iiraccordance Marnie invention, the drain returnline 41 includes a drain fitting 43 comprising a threaded bolt 47 whichis secured into one section 49 of the wall means 30 and which includesan axial bore or aperture fixedly carrying an axially extending tube 51.At the end of the tube 51 adjacent to the head 53 of the bolt 47, thetube 51 is provided with a nipple 57 which is connected to a tubularconduit 59 which, in turn, connects with the crankcase 31. The other endof the tube 51 includes an end 61 which terminates in spaced closelyadjacent relation to and in opposing relation to a portion 63 of thewall means 30. Means such as shims or washers 67 between the wallsection 49 and the bolt head 53, or other known mechanical arrangements,can be provided for adjustably locating the end 61 of the tube 51relative to the wall portion 63 so as to obtain optimum results. In thespecifically disclosed arrangement, the end 61 is spaced from the wallportion 63 by about one-sixteenth of an inch. At least some of theadvantages of the invention are believed to be obtainable with spacingsof up to about approximately one-eighth of an inch.

in order to minimize the internal volume of the drain return line 41 andthereby to maximize the responsiveness of the drains in the tube 51 tothe pressure pulses supplied to the drain line 41 from the crankcase 31,and thereby also to maximize the delivery velocity of the drains fromthe drain tube 51, in accordance with the invention, the respectivebores 71 and 73 of the tube 51 and the conduit 59 are relatively smallfor substantially the entire distance from the crankcase 31 to thetransfer passage 29. In the particularly disclosed construction, thebores 71 and 73 have a diameter of approximately one-sixteenth of aninch. At least some of the advantages of the invention are believed tobe obtainable with bores having diameters of up to about one-eighth ofan inch.

In operation, the discharge velocity of the drains provided as a resultof crankcase pressure and the relatively small diameter of the bores 71and 73, as well as the closely adjacent relation of the end 61 of thetube 51 relative to the wall portion 63, cause the returning stream ofdrains to splash when the stream hits the wall portion 63 and thereby tobreak up into many small droplets which can be readily carried, eitheras particles or as vapor, into the cylinder 17 by the incoming charge offuel-air mixture.

Thus, in the disclosed construction, the nozzle length is designed so asto spray the liquid fuel drainings directly against a non-water cooledportion of the cylinder wall and directly into the high velocity gaseousmixture just outside of the cylinder intake port. The

- fuel is thereby vaporized and carried into the cylinder where it isburned with the rest of the mixture.

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:

1. A two-stroke internal combustion engine including a cylinder, wallmeans defining a fuel supply passage communicating with said cylinder,and a drain return line communicating with a source of fuel drains andsupported by said wall means and including an end part having a borewith a diameter less than about oneeighth of an inch and terminating inspaced opposing relation to one portion of said wall means at a distanceless than about one-eighth of an inch, whereby drains exiting from saidreturn line splash against said wall portion and are broken intodroplets for delivery to said cylinder.

2. An engine in accordance with claim 1 wherein said engine alsoincludes a crankcase, wherein said fuel supply passage comprises atransfer passage communicating with said cylinder and said crankcase,and wherein said drain return line communicates with said crankcaseduring periods of positive pressure in said crankcase.

3. An engine in accordance with claim 2 wherein said drain return linehas a bore with an internal diameter of approximately one sixteenth ofantitank leading from said crankcase to said transfer passage.

4. An engine in accordance with claim 1 wherein said end part is spacedat about one-sixteenth of an inch from said wall portion.

5. An engme in accordance with claim 1 wherein said drain return linecomprises a tube including said end part and having a bore with adiameter of about onesixteenth of an inch.

6. An engine in accordance with claim 1 wherein said drain return lineincludes a conduit and a fitting comprising a bolt which includes a headand an axial bore and which is threaded into one section of said wallmeans and a tube fixed in said bore and including, at the end oppositefrom'said head, said end part and, at the end thereof adjacent saidhead, a nipple connected to said conduit.

7. A two-stroke internal combustion engine including a cylinder, acrankcase, wall means defining a fuel transfer passage communicatingbetween said crankcase and said cylinder and a drain return linesupported by said wall means and extending from and communicating withsaid crankcase, said drain return line including a conduit having anaxial bore communicating with said crankcase and a fitting comprising abolt which includes a head and an axial aperture and which is threadedinto one section of said wall means, and a tube which is fixed in saidbolt aperture, which includes at the end thereof adjacent said head, anipple connected to said conduit, which includes, at the other end, anend part terminating in opposed relation to one portion of said wallmans at a distance therefrom of about 1/16 of an inch, and which has anaxial bore communicating with said conduit axial bore, said axial boreshaving a diameter of about l/l6 of an inch.

1. A two-stroke internal combustion engine including a cylinder, wall means defining a fuel supply passage communicating with said cylinder, and a drain return line communicating with a source of fuel drains and supported by said wall means and including an end part having a bore with a diameter less than about one-eighth of an inch and terminating in spaced opposing relation to one portion of said wall means at a distance less than about oneeighth of an inch, whereby drains exiting from said return line splash against said wall portion and are broken into droplets for delivery to said cylinder.
 2. An engine in accordance with claim 1 wherein said engine also includes a crankcase, wherein said fuel supply passage comprises a transfer passage communicating with said cylinder and said crankcase, and wherein said drain return line communicates with said crankcase during periods of positive pressure in said crankcase.
 3. An engine in accordance with claim 2 wherein said drain return line has a bore with an internal diameter of approximately one-sixteenth of an inch extending substantially from said crankcase to said transfer passage.
 4. An engine in accordance with claim 1 wherein said end part is spaced at about one-sixteenth of an inch from said wall portion.
 5. An engine in accordance with claim 1 wherein said drain return line comprises a tube including said end part and having a bore with a diameter of about one-sixteenth of an inch.
 6. An engine in accordance with claim 1 wherein said drain return line includes a conduit and a fitting comprising a bolt which includes a head and an axial bore and which is threaded into one section of said wall means and a tube fixed in said bore and including, at the end opposite from said head, said end part and, at the end thereof adjacent said head, a nipple connected to said conduit.
 7. A two-stroke internal combustion engine including a cylinder, a crankcase, wall means defining a fuel transfer passage communicating between said crankcase and said cylinder and a drain return line supported by said wall means and extending from and communicating with said crankcase, said drain return line including a conduit having an axial bore communicating with said crankcase and a fitting comprising a bolt which includes a head and an axial aperture and which is thReaded into one section of said wall means, and a tube which is fixed in said bolt aperture, which includes at the end thereof adjacent said head, a nipple connected to said conduit, which includes, at the other end, an end part terminating in opposed relation to one portion of said wall mans at a distance therefrom of about 1/16 of an inch, and which has an axial bore communicating with said conduit axial bore, said axial bores having a diameter of about 1/16 of an inch. 